Six batches of 24 sows were used to study the impacts of the feeding schedule (alternative frequency and time, group M) or the diet (alternative net energy content (NE) and NE to metabolizable energy (ME) ratio, group D) on performance, either under natural summer heat wave situation (trial 1, 2 batches) or chronic heat stress induced with a fan setpoint kept at 25 °C (trial 2, 4 batches). Control sows (group C) and group D were fed 4 times a day between 7:30 am and 8:00 pm and group M 6 times between 6:30 pm and 12:00 am. The diet delivered to groups C and M was formulated at 9.5 MJ NE/kg with a NE/ME ratio of 73.6%. Corresponding values were 10.3 MJ/kg and 76.3% for group D. At farrowing and weaning, Sows and piglets were weighed, and backfat (BT) and muscle (MT) thicknesses were measured by ultrasound. Sows suckled 14.7 and 14.6 piglets on average in trials 1 (P=0.78) and 2 (P=0.77), respectively. Litter growth rate was not influenced by treatments in trial 1 (3.08 kg/d, P=0.42) and 2 (2.99 kg/d, P=0.35). In trial 1, a small number of heat waves of limited intensity occurred either during the first or the second half of the lactation depending on the batch, but the cumulated spontaneous NE intake was significantly higher in groups D and M than in group C (1,616, 1,512 and 1,325 MJ NE/sow, respectively, P=0.04). However, the difference in BW, BT and MT losses was not statistically significant (-39, -38 and -40 kg, P=0.88; -4.5, -5.2 and -4.6 mm, P=0.67; -4.6, -4.9 and -7.1 mm, P=0.56). In trial 2, the NE intake was higher in group D than in groups M and C (1,708, 1,398 and 1,428 MJ NE/sow, P<0.001) and associated to a lower MT loss (-4.1, -9.9 and -8.6 mm, respectively, P=0.007) but no difference in BW loss (-38, -40 and -43 kg, P=0.41) and BT loss (-4.1, -4.8 and -4.7 mm, P=0.34). In conclusion, these results demonstrate that a low thermogenic diet can help to increase NE intake when sows are exposed to heat waves and chronic heat stress, while changing the meal delivery increases feed intake only under heat waves. More data are expected under heat waves to characterize more precisely the interest of alternative feeding strategies on maternal body reserves and piglets.